In non-VSAM data set catalog entries, there is a pointer to the data set's DSCB. This allows the system to locate the data set more quickly than can be done through a VTOC search. When a non-VSAM data set is allocated, if the pointer does not point to the correct DSCB, allocation marks the data set so that the data set can be recataloged when it is deallocated. When the data set is deallocated, it is recataloged with the information gathered at allocation time.

Normally, this maintains correct information in the catalog. However, if you move a data set or otherwise update the catalog entry for a data set, and allocation has marked the data set to be recataloged at deallocation, the updates you made to the catalog entry are lost. Deallocation does not recognize that you have changed the entry.

For example, if you move a system data set, and allocation had marked that data set to be recataloged at deallocation time, the data set is recataloged with the volume serial number of the old volume, not the volume you moved it to.

There is no way to prevent this problem. To repair the catalog entry, simply delete the entry with DELETE NOSCRATCH, and recatalog the data set with DEFINE NONVSAM.